Porphyrin Conjugated Polymer Grafted onto BiVO₄ Nanosheets for Efficient Z‐Scheme Overall Water Splitting via Cascade Charge Transfer and Single‐Atom Catalytic Sites

Abstract

This work shows a novel artificial Z‐scheme photosystem based on a heterometallic Zn‐/Pt‐porphyrin conjugated polymer (ZnPtP‐CP) grafted onto ultrathin BiVO4 nanosheets via Zn–O–V bridging bonds for high‐efficiency overall water photosplitting. An impressive apparent quantum yield of 9.85% at λ = 400 nm is achieved over the resulting ZnPtP–CP/BiVO4 composite, in which BiVO4 nanosheets are in close contact with ZnPtP‐CP nanosheets via Zn–O–V bridging bonds to promote a Z‐scheme charge transfer mechanism with ZnPtP‐CP serving as electron‐rich unit and BiVO4 as hole‐rich one. The photoexcited electrons of BiVO4 transfer to the interface and recombine with the photogenerated holes of ZnPtP‐CP through the Zn–O–V bonds, and thus the strong reducibility of the photoinduced electrons in ZnPtP‐CP and the strong oxidation ability of the photogenerated holes in BiVO4 are maintained. Moreover, the highly dispersed Pt centers (PtN4) in Pt‐porphyrin bridging units act as single‐atom catalytic sites to facilitate a cascade charge transfer by fast migration of the photogenerated electrons from Zn‐porphyrin to Pt‐porphyrin units for the water reduction reaction. This Z‐scheme mechanism with two‐step excitation and cascade charge transfer pathway makes the composite acting as Z‐scheme dual‐function photocatalyst responsible for the efficient solar‐driven overall water photosplitting without the aid of a sacrificial reagent or external bias.

Sulfur‐Deficient ZnIn2S4/Oxygen‐Deficient WO3 Hybrids with Carbon Layer Bridges as a Novel Photothermal/Photocatalytic Integrated System for Z‐Scheme Overall Water Splitting

“…[8][9][10][11] Although numerous strategies have been applied to enhance the optical absorption and the charge separation efficiency of photocatalysts, including the structural design and defect engineering of materials, [12][13][14] the construction of hybrid materials, [15][16][17] and the deposition of effective cocatalysts, [18][19][20] a high solar-to-hydrogen (STH) efficiency in overall water splitting remains elusive (The widely reported STH efficiency is around 1%). [21][22][23][24] From the phase-interface perspective, the gas produced by water splitting in the conventional liquid/solid/gas triphase photocatalytic overall water splitting reaction is passively transported through the liquid water, which results in a low diffusion rate of the H 2 and O 2 gas in the liquid water. [25,26] Recently, our group fabricated a biphase reaction system in which wood as a photothermal substrate produces steam and the photocatalysts loaded on the wood simultaneously split the steam into H 2 .…”

Efficient CO2 reduction over a Ru-pincer complex/TiO2 hybrid photocatalyst via direct Z-scheme mechanism

“…, metal oxides, 2,4,5 metal sulfides, 3,6 and some other non-metal materials 5,7 ) have been developed as photocatalysts for CO 2 RR, the corresponding photoreaction systems containing single-component photocatalyst are facing certain huge obstacles, such as low productivity, variable products, severe thermodynamic conditions, and difficulty in meeting the energy band structure requirements for CO 2 RR and water oxidation at the same time in a reaction system. 2,5 To solve these problems, various strategies including constructing multi-component composites (such as heterojunctions and Z-scheme systems 7–11 ), modifying the surface chemistry, and extending the spectral response region (such as cocatalyst loading and dye sensitization 4,5,9,12 ) have been explored. Among them, the construction of artificial Z-scheme systems mimicking natural photosynthesis is an effective and facile strategy, whereby the photosystem (PS) I and PS II of natural photosynthetic systems are replaced by two semiconductors that can be excited simultaneously, and the photoinduced electron transfer path follows the letter “Z” shape, similar to the natural photosynthesis, which can not only promote the charge separation but also maintain the high reduction ability of PSI and the high oxidation capacity of PS II.…”

Wrapping BiVO4 with chlorophyll for greatly improved photoelectrochemical performance and stability

“…Additionally, the narrow optical response and high recombination rate of inorganic semiconductors restrict their exploitation in photocatalysts [20]. In contrast, organic species can be diversified by adjusting the molecular chemical structure [21,22], bringing special properties with multiplicity and maneuverability, which can meet different application requirements with low-cost inputs [23,24]. Furthermore, unlike combining inorganic semiconductors, combining surface hybrid photoanodes with organic materials to form an interface results in materials with more unique advantages, such as fewer intrinsic defects, better absorption characteristics, and excellent electrical properties [25][26][27].…”

“…Furthermore, unlike combining inorganic semiconductors, combining surface hybrid photoanodes with organic materials to form an interface results in materials with more unique advantages, such as fewer intrinsic defects, better absorption characteristics, and excellent electrical properties [25][26][27]. In recent years, many organic compounds (e.g., polyanilines [28], porphyrins [29], benzaldehyde [30], Zn-Pt-porphyrin conjugated polymers [21], and others [31]) have been applied in PEC water splitting.…”